As is known, in the usual by-product coke oven installation, an oven chamber is bounded on opposite sides by heating flues where coke oven gas or the like is burned to produce heat which passes through the oven walls to the coal being coked. In the heating flues, the combustible gas is introduced by means of nozzles extending upwardly from the sole of the flues. Inserted into these nozzles are refractory tubes of varying heights which produce flames at various heights within the flue to achieve a uniform heating pattern.
In the past, the various heights of the burner tubes could not be altered after initial construction of the coke oven installation. This is a disadvantage in that heating conditions may vary considerably with the kind of heating gas used and with the type of coal to be coked. It is, therefore, desirable, in order to produce a desired distribution of heat in the heating flues to provide a means for changing the heights of the burner tubes after the initial construction of the oven installation to accommodate different types of heating gases and coals to be coked.
In the past, arrangements such as that shown in German Pat. No. 480,746 have been devised for varying the heights of the burner tubes wherein interchangeable burner tubes of various heights are designed to be introduced downwardly from the roof of the oven through openings above the heating flues and then attached to burner nozzles permanently installed in the bottoms of the flues. The system disclosed in German Pat. No. 480,746, however, is impractical under present-day operating conditions for various reasons. The nozzles described in the aforesaid German patent, which are made of silica, are too large to be introduced through the presently-used inspection holes which are provided in the roof of the oven above the heating flues. While it would be possible to increase the inspection hole diameter, this would increase radiation losses excessively and impair the construction of the roof in other respects. Furthermore, tubes formed from silica as described in German Pat. No. 480,746, will crack and be destroyed if exposed suddenly to the temperature of the heated flues.
Whereas, by product coke ovens constructed 50 years ago had oven chamber heights no greater than about 4 meters, present-day ovens have chamber heights as great as 6 to 8 meters. This feature alone makes it much more difficult to achieve uniform heating along the length and height of the oven. Accordingly, a need exists to provide a means whereby the bottoms of the gas flames in the heating flues can be varied vertically, particularly since the requirements for uniform heating have increased to the extent that only very small temperature differences are permitted in the various layers of the coke cake before pushing.